The most commonly invoked power source of Active Galactic Nuclei (AGN) is accretion of galactic gas (probably through a disk) onto a supermassive black hole in the center of the nucleus (Rees 1984). As is well known, a black hole is completely defined by its mass and angular momentum. The unification scheme of active galaxies assumes that two known Seyfert types (Sy1 and Sy2) are not intrinsically different, i. e. their black hole masses, accretion rates and the whole internal structures are identical (Antonucci 1993) and observed differences are due just to a different orientation to the observer of the axisymmetrical central structure (central engine, BLR and thick torus, shadowing broad lines from some directions).
The Supermassive Black Hole Masses of Reverberation-mapped Active Galactic Nuclei
